Disc harrows ordinarily comprise at least one disc section including a plurality of spaced-apart disc blades mounted on a section shaft which is rotatably supported by the disc harrow. Spacer spools ordinarily are positioned between adjacent disc blades. In years past, the section shaft had a square configuration with each of the disc blades having a square opening formed in the center thereof which received the shaft extending therethrough. Many of the previous spacer spools also included a square opening formed therein which received the shaft. In those disc harrows employing square shafts, it was not a problem to prevent relative rotation between the disc blades, spacer spools and shaft. However, the problems connected with the fabrication of square shafts have led many disc harrow manufacturers to utilize round shafts rather than square shafts. It has been found that it is much easier to produce round shafts than to produce square shafts.
The use of round shafts in disc sections creates a serious problem in that relative rotation is experienced between the disc blades and the spacer spools as the disc harrow is moved through the field. Attempts are made to prevent such relative movement by tightening the nut at the end of the shaft but is practically impossible to apply sufficient torque to the nut to prevent such rotation. Relative rotation between the spacer spools and the disc blades creates wear on the ends of the spacer spools which results in the need for constant tightening of the shaft nut. It is only a question of time before the spacer spools must be replaced due to the wear on the ends thereof.
Therefore, it is a principal object of the invention to provide an improved spacer spool.
A still further object of the invention is to provide a spacer spool in combination with a disc blade wherein relative rotation is prevented between the spacer spool and the adjacent disc blade.
A further object of the invention is to provide a disc section for a disc harrow which permits the use of a round section shaft.
A further object of the invention is to provide a disc section which includes means for preventing relative rotation between the disc blades and spacer spools as the disc harrow is moved through the field.
A still further object of the invention is to provide a spacer spool which is economical to manufacture, durable in use and refined in appearance.